<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>
<body>
    
</body>
<script>
    let p=new Promise((resolve,reject)=>{
        setTimeout(() => {
            resolve(12)
        },1500);
    })
    p.then(num=>{
        alert(num)
    },error=>{
        alert('错误')
    })

</script>
</html>